Traditionally, fabrication of plastic parts and pieces has been expensive and time intensive due to the need to design and fabricate molds, as well as the limited accessibility of plastic fabrication equipment to the small scale manufacturer or those seeking to generate prototypes prior to large scale manufacture. In recent years, molding processes have benefited from advancements in computer aided design (“CAD”) and computer aided manufacturing (“CAM”) techniques, which has reduced costs associated with mold design, as well as reducing the time needed to generate high quality molds. Such computerized mold design does allow parts to be designed with higher probability that the plastic parts intended for fabrication therein will be both functional and can be manufactured. However, the parts themselves must still be fabricated in commercial manufacturing facilities, which require large upfront investment and are typically used as outsourced production resources for many parts and products manufacturers. In order to recoup the cost of the production facility, the manufacturer must typically add significant cost to the fabricated plastic part cost, which often can make smaller runs of parts cost prohibitive or, in the alternative, will increase the final product in which the fabricated plastic part will be incorporated. Moreover, it is generally not feasible to use such facilities for the fabrication of prototype parts due the cost and uncertainties associated therewith.
Additive manufacturing, which may be more commonly known today in the context of “3D Printing,” allows plastic parts to be made on a small scale by melting thermoplastic material and adding it layer by layer according to the specifications in a CAD drawing. 3D printing has the benefit of eliminating the need for mold creation and, accordingly, this methodology lends itself well to the fabrication of plastic parts on a scale that provides access to a wide variety of users. Indeed, 3D printing has substantially transformed the prototyping process in recent years, making it much easier to generate plastic parts to test their form and function on a small scale.
3D printing is nonetheless a very time consuming process, and therefore does not generally lend itself to use when more than a few pieces or parts are needed. For example, when small format 3D printers are used, it can take one hour or more to make a single part or piece using conventional processes. While commercial 3D printers are available to provide faster fabrication, such devices are expensive and, as such, are not readily available for general use. Thus, users today must trade off speed for cost and accessibility. This means that widely available 3D printers are generally used for rapid prototyping, especially prior to or in conjunction with mold design. Once the prototype configuration is finalized for manufacture, the CAD information is then used to prepare the mold for manufacture of the piece or part using conventional injection molding processes.
The proliferation of 3D printers in recent years, while important to allow the product design and prototyping processes to be substantially streamlined, still does not address the need to generate multiple finished pieces and parts in a short period of time using devices that are readily available to and more easily deployable by users.
Reaction injection molding is commonly used to fabricate pieces and parts where flexibility, softness and/or pliability is needed. Harder or foamed parts are also obtainable depending on the reactants used in a process. In a reaction injection molding process, two liquid components—“part A”, for example, a formulated polymeric isocyanate catalyst, and “part B”, for example, a formulated polyol blend, are mixed in a pressurized head and then pumped into a mold cavity. A reaction then occurs in the mold, resulting in a formed polymer part. Since these liquid or liquid-like materials require less pressure than other plastic fabrication methodologies, they can be injected into cost-efficient aluminum molds, lowering tooling costs. Additionally, such molding processes do not generally require substantial cooling of the molds. A further benefit is that the reactant materials can be varied to allow a myriad of physical properties to be imparted to the finished part. However, currently, reaction injection molding manufacturing processes are conducted on an industrial/commercial scale with catalyst and reactant stored in large storage tanks and dispensed by large, high-pressure industrial pumps.
The overall cost and complexity of existing reaction injection molding processes means that pieces and parts must generally be sent off-site for fabrication after the prototyping phase is complete, thus increasing the time and cost of part and piece fabrication. In short, notwithstanding the benefits of reaction injection molding processes in generating plastic parts for use in many products, this methodology is generally not accessible outside of commercial manufacturing facilities.
Moreover, commercial production of plastic pieces and parts often require only fairly small runs of from 1 to about 5000 pieces. When existing fabrication processes are used (i.e., mold fabrication followed by use of industrial scale plastic production facilities), runs of such a small size are expensive given the large purchase and operational costs associated with commercial reaction injection molding processes. Such background costs will necessarily cause the cost and manufacturing complexity of the final product that incorporates the piece or part to often be greatly magnified. Further, in many processes, manufacturing agility is needed. Early stage product production prior to moving to large scale production often requires evaluation of minor changes to the product to test various aspects of the product both in manufacturing and in use. Typically, the tooling costs associated with evaluating a minor variation in part and/or mold design has been an impediment to those making smaller run and/or lower cost molded products.
The movement toward “mass customization” in the marketplace also demonstrates a need for manufacturing agility. Runs of medical devices may need to be varied by size (e.g, small, medium or large) or customization of a lot of products for a particular patient may be required. Using traditional reaction injection molding processes, such flexibility is typically too expensive for all but the most expensive and/or highest volume products.
There remains a need for greater accessibility of users to reaction injection molding processes for fabrication of pieces and parts for use as finished products or as components in another product, especially where small production runs are contemplated. Moreover, there remains a need for users to be able to switch out reactant materials and molds on a smaller scale to allow flexibility in the ability to make pieces and parts having varied properties.